Muzzamil – I have looked at your site and it appears you running an outdated plugin which could be possibly causing you the problem.
Sexy Bookmarks, Sidebar Login, WP Page Navi and Count Per Day state that they are WordPress 3.1.1 compatible (although one of them hasn’t been updated in over a year). However, Syntax Highlighter Pro hasn’t been updated since Jan 2010 and is marked as compatible with WordPress 2.9.2.
Begin by deactivating that plugin to see if it is the issue and if so, look for a suitable replacement.
Hope this helps